Using simple rendering will break the ability to use various properties still available to SharePoint:AspMenu. Specifically:
- "DisappearAfter" attribute is not recognized -- menu will always disapear after the default time.
- "StaticDisplayLevels" and "MaximumDynamicDisplayLevels"are not recognized -- all menu items are output all the time.
Also, this isn't mentioned -- but setting UseSimpleRendering will ignore any styling and templating elements/attributes present. This is to be expected, I think -- as the styling should be done using CSS, styling the various classes.
- Styling attributes (i.e. StaticHoverStyle-BackColor, BackColor, etc.)
- Templating elements (i.e. StaticItemTemplate, DynamicItemTemplate, etc. )